1. Field of the Invention
The present invention relates to a conveying apparatus composed of a plurality of rollers, and more particularly relates to a conveying apparatus composed of a plurality of rollers and characterized by a controller that controls the operative performance of said conveying apparatus.
2. Relevant Prior Art
Various types of conveying apparatuses have widely been used in industries wherein each apparatus was composed of a plurality of rollers as illustrated in FIG. 13. This conveying apparatus 100 comprises a pair of frames 101 disposed in parallel with each other and supporting between them the rollers 102 and 103. Some of those rollers 102 are free rollers capable of rotating freely relative to their shafts. The other rollers 103 are each a motor-installed roller that has secured therein a motor and a speed reducer, so that this motor actuates each roller 103 to positively rotate about its axis.
Such a conveying apparatus 100 comprises also a plurality of sensors 105 arranged on and along the frame 105. Each sensor 101 such as a photosensitive sensor will detect every article advancing on and along the conveying apparatus 100.
The conveying apparatus 100 further comprises a terminal or distal controller 106 for controlling the operation of those motor-installed rollers (hereinafter called xe2x80x9cmotorized rollersxe2x80x9d) 103. A supervising or central control system such as a programmable controller not shown is connected to the terminal controller 106. The central control system will judge or determine whether any article is being conveyed on the apparatus 100, on the basis of data signals from the sensors 105. If any article is detected in this way, then the motorized rollers 103 will be actuated.
The so-called singulation mode and slug mode are known in the art as the methods of synchronously or simultaneously transporting a plurality of articles.
In the singulation mode, at least one empty or idle zone is interposed moment by moment between the two adjacent zones currently acting to transport the articles. Rollers of one zone will be put into operation, only where any article is detected on this zone, but no article is detected on the downstream zone.
In the slug mode, the formation of every row of the articles being conveyed does remain unchanged, during transportation of them from one zone to the adjacent downstream zone. Whether any article is present or absent on the downstream zone, the rollers of the one zone will be actuated. However, this principle does not apply to the downstream end region of such a transportation line.
Usually and ordinarily, a braking mechanism is installed in at least one of the rollers constituting such an end region. A brake shoe or the like will electrically be actuated to stop the roller""s cylindrical body due to friction thereof with said shoe, thereby causing every article to make a pause at such an end region.
The prior art conveying apparatus 100 necessitates the sensors 105 for detection of conveyed articles have to be disposed on the frame 101, in addition to the free and motorized rollers 102 and 103 in charge of transportation of the articles. In order to convey said articles accurately to their destinations, a lot of sensors 105 need to be attached to the frame 101. Thus, the conveying apparatus 100 must be constructed using many and various constituent parts such as the free and motorized rollers 102 and 103, the sensors 105, the terminal controller 106 and cables for connection thereof to these sensors. Such a considerably large number of constituent parts have rendered complicated the prior art conveying apparatus, consequently and problematically making it intricate and expensive to assemble the apparatus.
An object of the present invention made to resolve this problem is therefore to provide such a conveying apparatus that articles being conveyed on and along it can be detected without aid of sensors or any devices relevant thereto.
In order to achieve this object, and viewed from an aspect of the invention, it provides a conveying apparatus comprising a plurality of rollers for conveying an article, a motor for driving at least one of the rollers, and a controller for controlling the action of the motor. The controller comprises a rotation detector for obtaining an actual information with respect to rotating state of any of the rollers. The controller further comprises an article-state detector such that the actual information will be compared with a standard value representing normal rotations of the roller. On the basis of a difference thus found between the actual information and the standard value, current material state of the article being conveyed will be determined.
The term xe2x80x9crotating statexe2x80x9d used above does inclusively denotes velocity, direction, acceleration/deceleration, angular distance, duration and the like of rotation of the roller. The other term xe2x80x9cmaterial statexe2x80x9d does also inclusively denotes presence/absence of the article at any selected position of the apparatus, and weight of the article, as well as normality/abnormality in motion of the article being conveyed, and these definitions apply to the descriptions given hereinafter.
The present apparatus does not need any discrete sensors inherent in the prior art apparatuses, but nevertheless the material state can be detected to conduct adequate transportation of the article.
Due to elimination of the prior art sensors and relevant devices, the number of constituent parts is reduced in this conveying apparatus, rendering it simple in structure, easy to assemble and maintain, and thus inexpensive to manufacture.
Preferably, the rotation detector may be constructed such that the rotating state of the roller is determined based on an information indicating the rotational condition of the motor.
The term xe2x80x9crotational conditionxe2x80x9d just used above does inclusively denotes velocity, direction, acceleration/deceleration, angular distance, duration and the like of rotation of the motor.
The rotating state of the roller is thus easily obtained by directly obtaining the rotational condition of the motor. In a case wherein a speed reducer intervenes between the motor and roller, the motor will rotate at a higher speed than the roller. Even any slight change in the roller""s rotating state can be caught in this case based on such a direct detection of the motor""s rotational condition.
Preferably, the controller may determine whether any article is or is not present on the conveying apparatus, by comparing an actual rotating state of the roller with a preset reference value. This actual state is detected by the rotation detector as noted above, and the preset reference corresponds to an empty state of the apparatus not loaded with any article.
The actual rotating state of the roller is thus utilized to know the presence/absence of the article. Therefore, the present apparatus does no longer need any discrete sensors inherent in the prior art apparatuses, but nevertheless the material state can be detected to exactly transport the article to its desired destination.
The reference value to be preset may be obtained by measurement of idle rotations, i.e., rotations when loaded with no article, of the motor.
Also preferably, the controller may decide that the article has collided with any obstacle, when the rotation detector eventually outputs a much smaller number of rotations of the roller than a normal reference value.
Any accidents or events (such as jamming) that the article has collided with any obstacle will thus be detected automatically in this apparatus, thereby alarming an operator and/or turning off the motor so as to avoid energy loss and ensure smooth transportation.
Preferably, the controller may intentionally shift the rotational condition of the motor for the purpose of test, from stationary mode to forward rotary mode, or vice versa, from forward to reversed rotary mode, or vice versa, from a faster to a slower rotary mode, or vice versa. Any actual change found in the motor thus shifted, possibly with respect to load or the like parameter, will be used to know a current rotating state of the roller.
The article on the conveyor will not be able to follow such a sudden change in the rotating state of roller, with this change being caused by the shift of rotational condition of motor. In such an event, the roller""s inertial force acting on the motor will be added to a normal rotational resistance which the article is always imparting to this motor. If any article is on the roller, then a stronger braking force will be imposed on the motor, thus causing it to make a sharper change in its rotational condition. Conversely speaking, the presence/absence of article can be detected more precisely by causing the motor to make such an intentional and sudden change in its rotational condition.
Preferably, the controller may cause at given regular intervals of time, or periodically, the motor to make such an intentional and sudden change in its rotational condition in order to check the rotating state of roller.
Accurate detection of article will be enabled in such an electrical structure of the controller, without being affected by any variation in weight or shape of the articles.
Preferably, a signal pulse train may be generated in response to rotations of the motor that is driving the roller to rotate. The rotation detector in this case will count up the number of signal pulses output in a time from the motor to determine the actual rotational speed of the roller.
In the conveying apparatus of this type, the rotational speed and any change occurring therein will be detected surely, accurately and reliably. By virtue of this feature, the information on the rotating state of roller, particularly a change in its rotational speed, to know the state of the article then moving on and along the apparatus.
Also preferably, a signal pulse train may be generated in response to rotations of the motor, and the rotation detector will obtain the information on the roller""s rotating state on the basis of such pulses. The article-state detector in this case will compare the detected number of actual signal pulses with a reference number of pulses in idle operation. If the actual number is quite equal or nearly equal to each other, then this conveying apparatus will be regarded as being empty. The reference number of pulses may be one that has been determined based on measurement on this apparatus in idle operation without loaded with any article.
The term xe2x80x9cnearly equalxe2x80x9d just used above means that a difference found between the actual and reference numbers is the same as or smaller than a given limit. This limit may previously be obtained by experiments, and therefore a very simple standard is used herein to know whether any article is or is not on a particular module. The same or similar term and limit apply also to the following descriptions.
Also preferably, the signal pulse train may be generated in response to rotations of the motor, and the rotation detector monitoring the roller""s rotating state on the basis of such pulses. The article-state detector in this case will also compare the detected number of the actual pulses with the reference number of pulses for idle operation of said module. If a difference between the actual number and reference number is equal to or less than another limit, then the module of apparatus will be regarded as being loaded with any article.
Thus, a simple standard is used also in this case to know whether any article is or is not on a particular module.
Also preferably, a signal pulse train may be generated in response to rotations of the motor, and the rotation detector may monitor the roller""s state on the basis of such pulses. The article-state detector compares a reference value with the actual number of pulses having been counted up during a predetermined length of time just after operation of the motor for another predetermined length of time, so that if the actual number is less than the reference value, then the article on that module will be regarded as having collided with any obstacle.
Any jamming trouble of this apparatus will now be detected automatically in this way, so that the operator may be alarmed or the motor be stopped to ensure smooth transportation and avoid energy loss.
Further preferably, the signal pulse train may be generated in response to rotations of the motor, and the rotation detector monitoring the roller""s state also on the basis of such pulses. The article-state detector in this case will compare the actual numbers of pulses, one of which numbers been counted up during a unit time of forward operation, with the other actual number being measured after rotational direction is reversed. Also in this case, a difference found between these numbers will be utilized to know whether any article is present or absent on that module.
In a case wherein any article is moving on and along this apparatus, the article""s inertial force being imparted to the motor will be of such an intensity that it is difficult for this article to make a sharp change in rotational direction from forward to rearward. A difference found between the number of pulses generated during a period of forward rotations and that generated during rearward rotations will be rendered considerably larger, as compared with that which will be observed during this apparatus"" idle operation without any article thereon. Thus, such a difference will be useful to exactly judge presence/absence of said article.
The heavier the article on the conveying apparatus, the stronger is its inertial force acting on the motor so that the number of pulses which it generates will decrease noticeably. Weight of articles can be determined based on this fact.
Preferably, the rollers constituting the conveying apparatus may be put into operation, on condition that any article is on said apparatus.
Smooth transportation of articles along this conveying apparatus will be rendered sufficiently smooth in this way.
It also is preferable that the conveying apparatus of the invention does comprise a plurality of conveying zones arranged to form a row. Each conveying zone comprises a plurality of rollers for conveying an article, a motor for driving at least one of the rollers, and a controller for controlling the action of the motor. Each of such controllers disposed in the respective zones is adapted to receive the data or information generated in the adjacent zones with respect to presence/absence of the articles.
Each zone of this conveying apparatus has its own controller, so that the position of every article can be adjusted exactly even if it is shorter than each zone. During such transportation of short articles, the controllers in respective zones will function in harmony with each other. Respective articles are detected as to their position in the respective zones, and each group of rollers are turned on or off independently of the other groups of rollers. Those relatively short articles are thus conveyed successively and precisely in position, not to collide with each other.
Each controller in this apparatus will receive from the adjacent zones certain signals indicating presence/absence of any article or a portion thereof in those adjacent zones. Even if every article is relatively long and extends over one or more zones, it can be transported smoothly along this apparatus. This is because the controllers disposed in the adjacent zones will function in harmony with each other so that their groups of rollers are driven or stopped for example in a synchronous manner.
As just summarized above, each zone of this conveying apparatus has its own controller, and each controller in this zone will receive from the adjacent zones certain signals indicating presence/absence of any article or a portion thereof in those adjacent zones. Thanks to these characteristic features, any supervising controller such as programmable computers em-ployed in the prior art apparatuses can now be dispensed with, rendering the present apparatus simpler in structure and making it easy to change the layout of its conveying modules.
Preferably, each of the controllers may comprise an adjacent-zone inspector and an action commander. If and when the article is found on an upstream zone, an action commander in the controller of a downstream zone will generate and transmit a transportation commanding signal to another action commander in the other controller of the upstream zone. In this manner, the action commander in the upstream zone will operate to turn on the motor therein to drive and rotate the at least one roller belonging to the upstream zone.
In other words, a duty signal indicating the current state of downstream zone will be delivered to the upstream zone so as to drive the motor installed therein, causing the article to advance towards the downstream zone. In this way, position of articles being transported will be regulated precisely, protecting them from collision with each other.
Preferably, even while power supply to the motor remains cut off, the roller may possibly and forcibly be driven to rotate on condition that the rotation detector for that motor detects rotations thereof, resuming power supply to the motor.
In detail, if and when any article tends to enter a conveying apparatus or a zone thereof in issue from the adjacent apparatus or its zone, or if and when any external force is applied to any article on the apparatus in issue, the rollers will be driven positively to start rotation. Resultant passive rotations of the motor will then be detected by the rotation detector for this motor, resuming power supply even if it has been switched off. Thus, with any article coming from the upstream apparatus or a zone thereof, the rollers in the downstream zone will then be actuated to smoothly take the article into this zone. With any external or foreign force being intentionally applied to any article towards the downstream zone, the rollers will likewise be put into a positive motion, thus lowering magnitude of said foreign force.
Preferably, the apparatus includes at least one of the rollers that serves as a brake and is driven by a motor, which in turn is regulated by a controller. This controller comprises a rotation detector for monitoring rotations of the motor. This motor will be caused on demand to rotate in a reverse direction opposite to the normal direction of the roller""s forward rotations, thereby simply braking the roller.
In this case, the apparatus does not need any ordinary and electrically driven mechanical brake shoe or the like. Articles on this apparatus having been switched off will be ready to manual displacement while doing maintenance operations. The present braking mechanism devoid of mechanical brake shoes and discrete additional position sensors will render this apparatus simpler in structure, nevertheless enabling the article to make a temporary stop at any given point.
Preferably, at least one -of rollers constituting the conveying apparatus may be composed of a fixed shaft, a roller body capable of rotating freely relative to the shaft, and a motor accommodated in the roller body. A torque of the motor will be transmitted to the roller body, making it spin about the shaft, when the motor is actuated.
Such a motorized roller simplifies the apparatus and renders it compacted.
From a further aspect of the invention, it provides in order to achieve the object set forth hereinbefore a conveying apparatus comprising a plurality of rollers for conveying an article, a motor for driving at least one of the rollers, and a controller for controlling the action of the motor. The controller comprises a rotation detector for obtaining an actual information with respect to rotational condition of the motor. The controller further comprises an article-state detector such that the actual information will be compared with a reference value representing idle rotations of the motor. On the basis of a difference thus found between the actual information and the reference value, presence/absence of the article on the apparatus will be determined.
The rotation detector functions to depict the motor""s rotational condition adapted to know the presence/absence of the article on the apparatus. Thus, the present apparatus does not need any discrete and ordinary sensors inherent in the prior art apparatuses, nevertheless affording detection of the article and adequately transporting it to its desired destination.
Due to elimination of the prior art sensors and relevant devices, the number of constituent parts is reduced in this conveying apparatus, rendering it simple in structure, easy to assemble and maintain, and thus inexpensive to manufacture.
Preferably, the controller may intentionally shift the rotational condition of the motor for the purpose of test, from stationary mode to forward rotary mode, or vice versa, from forward to reversed rotary mode, or vice versa, from faster to slower rotary mode, or vice versa.
The article on the conveyor will not be able to follow such a sudden change in the rotational condition of motor. In such an event, the article""s inertial force acting on the motor will be added to a normal rotational resistance which the article""s weight is always imparting to this motor. If any article is on the roller, then a stronger braking force will be imposed on the motor, thus showing a sharper change in its rotational condition. Conversely speaking, the presence/absence of article can be detected more precisely by causing such a sudden change in rotational condition of motor.
Also preferably, a signal pulse train may be generated in response to rotations of the motor, and the rotation detector will obtain the information on the roller""s rotating state on the basis of such pulses. The article-state detector will compare the detected number of actual signal pulses with a reference number of pulses in idle operation. If the actual number is quite equal or nearly equal to each other, then this conveying apparatus will be regarded as being empty. The reference number of pulses may be one that has been determined based on measurement on this apparatus in idle operation without loaded with any article.
Such a simple standard is used herein to know whether any article is or is not on a particular module of the conveying apparatus.
Also preferably, the signal pulse train may be generated in response to rotations of the motor, and the rotation detector may obtain information on the roller""s rotating state on the basis of such pulses. The article-state detector in this case will also compare the detected number of the actual pulses with the reference number of pulses for idle operation of said module. If a difference between the actual number and reference number is equal to or less than another limit, then the module of apparatus will be regarded as being loaded with any article.
Thus, a simple standard is used also in this case to know whether any article is or is not on a particular module.
From a still further aspect of the invention, it provides a conveying apparatus that comprises a plurality of rollers for conveying an article, a motor for driving at least one of the rollers, and a controller for controlling the action of the motor. This controller may comprise a rotation detector for obtaining an actual information with respect to rotational condition of the motor, as well as a collision indicator such that a reference value is compared with the actual number of pulses having been measured during a predetermined length of time when the motor is expected to rotate, so that if the actual number is less than the reference value, then the article on that module will be regarded as having collided with any obstacle.
Jamming troubles of this apparatus will now be detected automatically in this way, so that the operator may be alarmed or the motor be stopped to ensure smooth transportation and avoid energy loss.
Preferably, the controller may intentionally shift the rotational condition of the motor for the purpose of test, from stationary mode to forward rotary mode, or vice versa, from forward to reversed rotary mode, or vice versa, from faster to slower rotary mode, or vice versa.
In this way, the presence/absence of article can be detected more precisely.